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The purpose of this paper is to design an oil-air lubrication system with low temperature rise, vibration and noise simplifies the spindle configuration. The oil-air lubrication unit is a key component for high-speed grinding machine tools. The development of oil-air lubrication unit suitable for high/ultrahigh rotational speed is a daunting task owing to the lubrication challenges.

This paper emphasizes three main issues: the analysis of oil-air two-phase flow for tradition oil-air lubrication unit with the simulation method; the design of new oil-air lubrication unit for the high/ultrahigh-speed grinding machine tools and the comparative experiment research of tradition and new oil-air lubrication unit. The optimum structure parameters that create the optimum flow pattern and operating conditions resulting in low temperature increase, vibration and noise of oil-air lubricated spindle can be achieved by the simulation method and experiments.

The simulation and experimental results show that new oil-air lubrication unit lubricating a high speed electric spindle has a better performance with a small temperature increase and vibration, which means that our proposed method is an effective design method for oil-air lubrication system.

A design method suitable for high-speed oil-air lubrication unit is proposed. New oil-air lubrication unit is expected to apply for high/ultrahigh rotational speed grinding machine tools.

The purpose of this paper is to investigate that if the lubrication system of a helicopter reducer is compromised, its gears and bearings will be at non-lubricating oil work state, which causes the reducer to be damaged in a very short time.

Various 2 per cent additives were injected and mixed with aeronautical oil to produce 45-min oil/mist lubrication and oil/air lubrication experiments performed upon aeronautical steel tribo-pairs.

The results show that the best anti-wear effect is produced by oil/air lubrication that contains 2 per cent T391. It consumes the least quantity of oil and produces the least wear width, the least rise in temperature and the best surface wear quality.

The technology of oil/air lubrication that contains an extreme-pressure and anti-wear additive is a feasible way to improve the operational ability of a helicopter transmission system that is out of oil.

The purpose of this paper is to improve the lubrication and remove as much as possible of the heat generated in the bearing assembly, embedded in the jet engine.

To determine the necessary values of the air pressure and oil amount, an experimental approach is used. For that purpose, a custom made test rig is developed.

Less amount of oil makes better lubrication conditions, reflected in the smaller temperature of the bearings. Concerning the air pressure, too high and too low air pressure deteriorates the lubrication parameters. An optimum value should be determined experimentally. The influence of oil amount is remarkably bigger than the influence of air pressure.

This experimental investigation provides an easy and fast way to improve the high-speed bearings lubrication parameters.

The purpose of this paper is to design the novel oil–air distributor (N-OAD). Its structure design, oil feeding reliability, service life and viscosity properties of air bubble (AB) oil were analyzed. Meanwhile, the formation mechanism of AB oil was established based on Kelvin–Helmholtz instability.

First, oil–air distributor (OAD) and N-OAD were randomly selected for testing when the air pressure was 0.25 MPa and oil feeding was 100 times per hour. Then, the bubbles were found in the lubricant during the experiment, and the void fraction and viscosity properties of AB oil were tested by image processing method and the MARS 40 rheometer, respectively.

N-OAD has longer service life and higher working reliability than OAD. The key factors of AB oil formation were air pressure and oil feeding. And the void fraction of AB oil has different results on the viscosity at high and low shear rates.

The outcome of this research paper gives an insight to improve the reliability of oil–air lubrication systems and the safety factor of machine tool spindle operation.

This series of articles continues the theme of Mr. Brewer's preveious series, “Lubrication—Management Responsibility” The series deals with the lubrication of industrial plant, but with the intention of ‘educating’ Management to the importance of ensuring that production is not lost because of faulty lubrication.

The purpose of this paper is to test mechanical face seals made of carbon/SS316 with different coolants for evaluating its tribological performance. The reliability of a mechanical seal mainly depends on the seal materials and the type of coolant used for the lubrication.

Compressed air, vacuum and nitrogen are the main coolants utilized for the experimental work, and the obtained results are compared with the dry running case for a specified period. The experimental results are also validated with the computational fluid dynamics (CFD) simulation results.

The results shows that the sealing pressure, sliding speed and materials used would be the predominant factors for the seal design. Over compressed air, vacuum and nitrogen cooling techniques were found to be more efficient.

The experimental results are also validated with the CFD simulation results. This paper also emphasizes the usage of vacuum as a cooling medium in industries, which will enhance the seal life at an economical cost over nitrogen.

For a lightweight and accurate description of bearing temperature, this paper aims to present an efficient semi-empirical model with oil–air two-phase flow and gray-box model.

First, the role of lubricant/coolant in bearing temperature was discussed separately, and the gray-box models on the heat convection inside a bearing cavity were also created. Next, the bearing node setting scheme was optimized. Consequently, a novel semi-empirical two-phase flow thermal grid for high-speed angular contact ball bearings was planned. With this model, the thermal network for the selected motored spindle was built, and the numerical solutions for bearing temperature rise were obtained and contrasted with the experimental values for validation. The polynomial interpolation on test data, meanwhile, was also performed to help us observe the temperature change trend. Finally, the simulations based on the current models of bearings were implemented, whose corresponding results were also compared with our research work.

The validation result indicates that the thermal prediction is more accurate and efficient when the developed semi-empirical oil–air two-phase flow model is employed to assess the thermal change of bearings. Clearly, we provide a more proper model for the thermal assessment of bearing and even spindle heating.

To the best of the authors’ knowledge, this paper introduced the oil–air separation and gray-box model for the first time to describe the heat exchange inside bearing cavities and accordingly presents an efficient semi-empirical oil–air two-phase flow model to evaluate the bearing temperature variation by using thermal network method.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0180/

There are two principal reasons why it is disadvantageous, and frequently dangerous, to over‐lubricate the cylinders of air compressors, firstly fire risk and secondly contamination of air with oil vapour. Control of oil feed will prevent any likelihood of explosive fires but it may be necessary to incorporate special oil vapour filters to prevent contamination of materials and products coming into contact with the compressed air.

A cross-platform paradigm (computing model), which combines the graphical user interface of MATLAB and parallel Fortran programming, for fluid-film lubrication analysis is proposed. The purpose of this paper is to take the advantages of effective multithreaded computing of OpenMP and MATLAB’s user-friendly interface and real-time display capability.

A validation of computing performance of MATLAB and Fortran coding for solving two simple sliders by iterative solution methods is conducted. The online display of the particles’ search process is incorporated in the MATLAB coding, and the execution of the air foil bearing optimum design is conducted by using OpenMP multithreaded computing in the background. The optimization analysis is conducted by particle swarm optimization method for an air foil bearing design.

It is found that the MATLAB programs require prolonged execution times than those by using Fortran computing in iterative methods. The execution time of the air foil bearing optimum design is significantly minimized by using the OpenMP computing. As a result, the cross-platform paradigm can provide a useful graphical user interface. And very little code rewritting of the original numerical models is required, which is usually optimized for either serial or parallel computing.

Iterative methods are commonly applied in fluid-film lubrication analyses. In this study, iterative methods are used as the solution methods, which may not be an effective way to compute in the MATLAB’s setting.

In this study, a cross-platform paradigm consisting of a standalone MATLAB and Fortran codes is proposed. The approach combines the best of the two paradigms and each coding can be modified or maintained independently for different applications.

Limited volume lubrication as applied in metal working operations has grown significantly in the South African manufacturing industry over the past years. The need for a cleaner factory environment and the international competition faced by local producers, necessitated a re‐evaluation of the efficiency of operations pertaining to tool life and quality of products. The technique started with sawing of aluminium and was extended through copper and stainless steel to mild steel manufacturing operations including band sawing, drilling and tapping, pressing and hot forging. The technique is limited by the material to be worked as well as the rate of metal working. Synthetic lubricants proved to be indispensable in meeting the challenges faced when applying the technique.